It is well known that tobacco smoke contains various alkaloids such as nicotine and volatile materials such as tar, which are believed to be physiologically harmful to a smoker. It is also known that the generation of these harmful materials is promoted by high temperature and that the heat itself is detrimental to the smoker's health. Various filters have been proposed to remove nicotine and tar, but none has been entirely satisfactory since they have either been substantially ineffective for those purposes or have produced a filtered smoke of inferior draw or taste. Commercially available prior art filters have been made from glass fibers, cellulosic fibers, activated charcoal or the like. In the case of ordinary sized cigarettes, these filters are usually 20 mm. in length and in king sized cigarettes the filters are generally 25 to 27 mm. long.
Various forms of kaolin clay have also been proposed for use in filters, but these forms differ from that utilized in the present invention. For example, U.S. Pat. No. 3,650,279 discloses a cigarette filter composed of a powdered aluminum silicate mineral which is prepared by rendering the mineral electropositive and then cationizing it by absorbing macromolecular cations (such as methylene blue and FeSO.sub.4) thereon. A further example of prior art uses of kaolin clays is U.S. Pat. No. 3,428,054 which relates to a cigarette filter composed of mineral particles, such as slag, and absorptive powdered clay, such as kaolinite, bound together by a non-toxic binder. A still further example of prior art uses of kaolin clay is U.S. Pat. No. 3,251,365 wherein a cigarette filter is disclosed composed of powdered clay, such as kaolin, into which from 1 to 13 percent by weight of iron or zinc oxide is incorporated. And finally, U.S. Pat. No. 2,967,118 shows a specially prepared kaolin clay powder which has been acid activated for use in filters. Powdered clays proposed for use as tobacco smoke filters as in the above-mentioned patents are believed to be only partially effective since they have a marked effect on draw resistance and taste of the smoke and for other reasons.